Probe assemblies or devices are often inserted in and removed from pressure vessels such as a pipeline for a variety of purposes. Such devices include, for example, corrosion coupons, corrosion probes, injection or sampling devices, and a wide variety of sensing, measuring and control devices. Sometimes the probe is threaded into a high pressure access fitting as seen in Applicants copending application Ser. No. 08/355,623, filed Dec. 14, 1994, and entitled High Pressure Access Fitting And Method.
Such probes are usually installed through a high pressure access valve by a high pressure retriever such as shown in Applicant's prior U.S. Pat. No. 4,537,071.
Probes or devices are also inserted or retrieved through sealed fittings such as a stuffing box or packer joint, and they are often done so with hydraulic tools or drives. Examples of hydraulic tools or drives are seen in U.S. Pat. Nos. 3,718,034, 3,812,722, 4,346,611, 4,387,592, 4,916,797, 4,930,361 and U.S. Pat. No. 5,385,060. Such tools are usually double acting, or if single acting rely solely on the pressure in the vessel for retrieval. Such tools usually require two people to complete the steps required. Cylinders with laterally extending fittings make the tool bulky and awkward and inhibit axial rotation of the tool, particularly once the tool is installed on a fitting. If a hydraulic spring return cylinder could be provided, the stroke of most conventional springs is far too short to have any range of applications, particularly since a stroke of a meter or more may be required in some applications. Moreover, the tools cannot quickly be attached to a probe containing stuffing box fitting, and then axially rotated with respect to the fitting to lock and unlock the probe with respect to the fitting.
Collets are widely used as gripping devices, and are sometimes employed in connection with the insertion and retraction of devices into and out of pressure vessels. Examples of such employment of collets may be seen in U.S. Pat. Nos. 4,275,592, 4,697,465, 5,106,580, and U.S. Pat. No. 5,138,755. Such collets and any related fittings are usually characterized by complexity and are not capable of locking or unlocking a device simply by rotating a tool axially of the fitting to which it is attached.
It would, therefore, be desirable to have a tool and an associated simplified stuffing box fitting where the assembled tool can be used to lock or unlock the device with respect to the fitting by limited axial turning of the tool itself.